Couplings of the conical type, such as Morse cones, are a well-known solution to assemble two pieces in a simple and disassembleable way. A conical coupling is constituted, as shown in FIG. 1, by a male member 1 and a female member 2, generally of metal. The male member 1 comprises a cone 3 fitted in a corresponding conical recess 4 of the female member 2. The male and female members 1, 2 are designed such that, when they are in coupled position, interstices e1, e2 remain between the distal end of the cone 3 and the bottom of the conical recess 4 and between the base, 5, of the female member 2 and the upper plane or shoulder, 6, of the male member 1, so as to obtain a wedging of the cone 3 in the recess 4 and to avoid making the coupling hyperstatic. These interstices e1, e2 must remain over all the range of use of the coupling. In other words, the male and female members 1, 2 are designed to resist forces of penetration of the male member 1 into the female member 2 no matter what the axial compression loads that may be applied to the coupling.
This type of coupling ensures an effective centering and blocking in rotation of the male member relative to the female member. However, it requires producing the female member of a material that is very resistant in tension. Indeed, because of the angle of the cone 3 and of the axial compression force necessary to produce the coupling, i.e. to assemble the male and female members, the lower portion of the female member in contact with the cone 3 is permanently subjected to tension forces T, which increase when, during use, the coupling is subjected to axial compression loads F.
Thus, while such couplings are suitable for male and female members that are made of metal and which thus have high resistance in tension, their principle seems to be difficultly transposable to applications in which the coupling would be subjected to large axial compression loads F, such as those received for example by certain prostheses, and the material of which the female member would be made would have poor resistance in tension. In such cases, indeed, the female member would break at the level of its lower portion, under the action of tension forces T, as soon as the maximum tensile strength limit of the material constituting the female member is exceeded.